1. Technical Field
The embodiments described herein generally relate to a dual energy-storage for a vehicle system.
2. Background Art
Conventional micro/mild hybrid vehicles each include a starter-generator unit and a conventional 14 Volt electrical architecture. The hybrid vehicle is also equipped with a plurality of energy-storage devices. For example, the energy storage devices may include a plurality of batteries and a supercapacitor bank. With such a configuration, the vehicles can efficiently handle the electrical-energy flow to and from the energy storage devices and provide stop-start, regenerative braking and power boost functionality in order to reduce average fuel consumption and CO2 emissions. The conventional method for interfacing with the energy-storage devices includes implementing a combination of relays or a DC/DC converter. The relays allow for the transmission/consumption of energy to/from a starter generator. The relays transmit/receive power to/from different power nets in the vehicle. Each power net is connected to an energy storage device via a separate relay. Such a configuration may only support engine stop-start functionality.
The DC/DC converter is a more flexible solution since the DC/DC converter provides a seamless permanent interface between the two energy storage devices (e.g., the battery and the supercapacitor bank). In addition, the DC/DC converter can adapt voltage differences from each side of the DC/DC converter and operate bidirectionally. The DC/DC converter solution makes it possible not only to perform the stop-start function but the DC/DC converter also allows the vehicle to perform regenerative braking and support power boost features. While the DC/DC converter is useful, the DC/DC converter is complex-to-manufacture and may require an expensive electronic unit to control the operation of the DC/DC converter.
The typical DC/DC converter for the aforementioned application is a bidirectional 12-to-12 volt stabilizer which is able to handle different voltage ranges at the input and output of the DC/DC converter. The DC/DC converters are usually designed with a power-electronics topology that uses power semiconductors along with drivers, magnetic components (which include transformers or inductors) and a controller board.
Accordingly, it would be desirable to implement a simple interface between energy storage devices in a hybrid vehicle. It would also be desirable to provide a controller device that may be less complex and inexpensive to implement than the conventional DC/DC converters as implemented in hybrid vehicles.